Math Problem Statement

the quadratic function y=a*(x-b)^2+c passes through the points (-2,0) and (6,0). its maximum value y is 48. find the values of a, b, and c

Solution

We are given a quadratic function in the form:

y=a(xb)2+cy = a(x - b)^2 + c

with the following information:

  1. The function passes through the points (2,0)(-2, 0) and (6,0)(6, 0).
  2. The maximum value of yy is 48.

Step 1: Use the fact that the function passes through the points

Since the quadratic passes through the points (2,0)(-2, 0) and (6,0)(6, 0), we know these are the roots of the quadratic. Therefore, the vertex of the parabola lies halfway between these two points.

The midpoint between (2,0)(-2, 0) and (6,0)(6, 0) is:

b=2+62=2b = \frac{-2 + 6}{2} = 2

Thus, the value of bb is 22, which represents the xx-coordinate of the vertex.

Step 2: Use the maximum value of yy

The maximum value of the quadratic is given as 48. Since the vertex occurs at x=2x = 2, substitute x=2x = 2 and y=48y = 48 into the equation y=a(xb)2+cy = a(x - b)^2 + c:

48=a(22)2+c48 = a(2 - 2)^2 + c 48=0+c48 = 0 + c c=48c = 48

Thus, c=48c = 48.

Step 3: Use the fact that the points (2,0)(-2, 0) and (6,0)(6, 0) are on the curve

We now know that the quadratic passes through the points (2,0)(-2, 0) and (6,0)(6, 0), so we can substitute one of these points into the equation to find aa. Let's use the point (2,0)(-2, 0):

Substitute x=2x = -2 and y=0y = 0 into the equation:

0=a(22)2+480 = a(-2 - 2)^2 + 48 0=a(4)2+480 = a(-4)^2 + 48 0=16a+480 = 16a + 48 16a=4816a = -48 a=3a = -3

Final Answer:

The values of aa, bb, and cc are:

a=3,b=2,c=48a = -3, \quad b = 2, \quad c = 48

Would you like a more detailed explanation of any step, or do you have any further questions?


5 Related Questions:

  1. How does the value of aa affect the orientation of the parabola?
  2. What happens to the quadratic if the vertex value y=48y = 48 were increased or decreased?
  3. How can you write the equation of a quadratic in standard form from its vertex form?
  4. How do you determine the axis of symmetry of a quadratic function?
  5. How can you find the roots of a quadratic equation if the vertex and maximum value are known?

Tip:

When a quadratic function is in vertex form, y=a(xb)2+cy = a(x - b)^2 + c, the vertex is located at (b,c)(b, c), and the axis of symmetry is the vertical line x=bx = b.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Functions
Vertex Form of a Quadratic Function

Formulas

y = a(x - b)^2 + c

Theorems

Vertex of a Parabola
Maximum/Minimum Value of a Parabola

Suitable Grade Level

Grades 8-10